1. Field of the Invention
The present invention pertains to sailboats and, more particularly, to boom brakes for controlling the swinging motion of the booms of sailboats.
2. Discussion of the Prior Art
A jibe occurs when a sailboat changes course in a following or quartering wind. For example, if the wind is coming over the port, or left, rear quarter and the boat heads to starboard, the wind will then come over the starboard rear quarter requiring the sails to be reset. In the case of the mainsail, the mainsheet is pulled in until the mainsail fills on the other side, at which point the mainsail is let out to the correct position. An accidental jibe occurs when the boom swings freely across the deck because of a sudden change in wind direction, helmsman error or unexpected wave action. As the sail begins to fill on the new side in an accidental jibe, the mainsheet no longer restrains the boom, so the boom can very quickly gather a considerable amount of speed, and in one to three seconds from the start of the accidental jibe, the boom can pass over the cockpit. There is very little time to react, and the boom often weighs 40 to 60 lbs on an average boat. If someone is in the way, he or she will, at the least, receive an unpleasant knock, and can be killed by impact or knocked overboard as happens to sailors every year. One option to prevent such boom swings is to set a preventer, a line run from the boom forward, but such a line can be difficult to release offshore, especially at night and/or in rough conditions when the preventer line is needed most. Furthermore, when the preventer line is released an anxious moment is created as the crew tries to get the boom in.
Prior art sailboat boom motion control, as exemplified by U.S. Pat. No. 4,138,962 to Waelder, has utilized a brake line secured at opposite ends to the gunwales of the sailboat and passing through a device mounted on the boom for retarding the passage of the line by frictional resistance of one or more dead turns of the line around a fixed non-rotatable sheave. Retardation of the line is adjusted by removing or adding additional turns of the line around the fixed sheave; however, such adjustment is time consuming in all instances and difficult in rough weather. For coastal sailing, which generally requires frequent jibing and wind condition changes, such a procedure to appropriately adjust the brake resistance is unsatisfactory. In another approach, the brake line passes around a rotatable sheave with pivotable brake shoes disposed to bear against the inner surface of the sheave. The brake shoes are linked to the boom so that as the boom rises in response to increased wind pressure on the sail, the brake shoes are urged with increasing force against the sheave inner surface to retard the rotation of the sheave and increase the resistance of the device to passage of the brake line. Both of these approaches have the disadvantages of requiring expensive machined components and not being simply and adequately adjustable to change brake line resistance.
U.S. Pat. No. 4,941,420 to Heintz is exemplary of simpler boom brakes in which the frictional resistance to the passage of a line between the boat gunwales is developed by a turn or turns of the line around a non-rotatable smooth drum mounted on the boom. In practice, such boom brakes develop very rapid buildups of frictional resistance due to the flattening of the line against the flat drum sharply narrowing the range of boom motion control available. Multiple turns of the brake line around the drum create the problem of overwrapping of the line and jamming of the brake. Machining helical guide grooves in the drum surface to overcome the problem caused by overwrapping has the disadvantage of being expensive.